Key takeaways
- I’ll be honest about one thing I’m not certain of up front and then write the article straight.Table of ContentsWhat actually matters in a metal-drilling bit setThe titanium coating thingComparing the realistic optionsWhat to actually buyThe technique that saves bits…
What's inside
I’ll be honest about one thing I’m not certain of up front and then write the article straight.
Most drill bits sold in hardware store multi-packs are not actually good at drilling metal, even though the packaging shows them cutting through a steel plate. The bit geometry and material in a $12 set of 20 “general purpose” bits is optimized for wood and the occasional screw hole, not steady contact with mild steel or stainless. If you’re drilling metal more than a few times a year, the set you buy matters more than almost any other factor in whether the job goes smoothly or turns into broken bits and burnt-out holes.
What actually matters in a metal-drilling bit set
Three things determine whether a bit set is worth buying for metal: the steel the bit is made from, the tip geometry, and whether it’s actually sized consistently (cheap sets drift on size more than you’d expect).
For material, you want cobalt (M35 or similar) or high-speed steel (HSS), not black oxide-coated low-carbon steel. Black oxide bits are fine for wood and plastic and will survive a handful of holes in thin mild steel, but they dull fast and the coating wears off almost immediately under heat. Cobalt bits hold an edge through much higher temperatures, which matters because drilling metal generates real heat even with lubricant. If you’re working with stainless steel at all, cobalt isn’t optional — standard HSS will glaze over and stop cutting within a few holes.
Tip angle matters too. A 118-degree point is the standard compromise angle found in most general sets. A 135-degree split point is better for metal because it starts cutting on contact instead of wandering, which is the single most common failure mode beginners hit — the bit skates across the surface, leaves a scratch, and never finds purchase. If a set lists its point angle at all, that’s usually a sign it was actually designed with metal in mind rather than being a wood bit sold into every category.
The titanium coating thing
Titanium nitride (TiN) coated bits show up in almost every set marketed for metal, and the coating does reduce friction and add some surface hardness. But it’s a thin coating over whatever base steel is underneath. If the base is cheap steel, the coating wears through in the first dozen holes and you’re left with a bit no better than uncoated. Titanium coating on a cobalt base is genuinely good. Titanium coating on carbon steel is mostly marketing. Check what’s under the coating, not just the color of the bit.
Comparing the realistic options
| Type | Good for | Struggles with | Typical lifespan drilling steel |
|---|---|---|---|
| Black oxide HSS | Thin sheet metal, occasional holes, aluminum | Stainless, repeated use, anything over 1/8″ in steel plate | 10-20 holes before noticeably dull |
| Cobalt (M35) | Mild steel, stainless, repeated/production use | Price, more brittle if flexed sideways | 100+ holes with lubricant and correct speed |
| Carbide-tipped | Hardened steel, masonry-adjacent metal work | Overkill and expensive for routine jobs, brittle if not run straight | Very long if used correctly, can shatter if misused |
| Step bits (cobalt) | Sheet metal, electrical boxes, variable hole sizes | No good for anything thicker than ~1/4″ | Long, low wear per use since cutting edge is short per step |
What to actually buy
For most people doing home or shop projects — brackets, hinges, the occasional stainless project — a cobalt bit set covering 1/16″ to 3/8″ or so is the right call. You’ll pay more than the hardware store multi-pack, but one decent set will outlast five cheap ones and actually cut cleanly instead of burning and squealing. Search for a cobalt drill bit set for metal and look for ones that specify M35 cobalt content and a 135-degree split point in the listing, not just “metal drilling” in the title.
If you’re mostly working with thin sheet metal — electrical boxes, HVAC ducting, car body panels — a step drill bit set is actually a better buy than a standard twist bit set. One step bit replaces a dozen fixed sizes, won’t grab and spin the sheet metal the way a twist bit can, and deburrs the hole as it goes.
If your work is occasional — you need to drill three holes in an angle bracket once a year — don’t overspend. A basic black oxide set from a hardware store will do that job fine, as long as you run the drill slow, apply light cutting oil, and don’t expect it to go through stainless. Buying a $60 cobalt set for three holes a year is money better spent elsewhere.
Where it’s worth spending more regardless of frequency is stainless steel. Stainless work-hardens as you drill it, meaning if you go too slow or stop mid-hole, the material gets harder right where you’re cutting and the bit just stops working. A quality cobalt bit, steady pressure, slow speed (under 500 RPM for anything over 1/4″), and constant cutting fluid are the difference between a clean hole and a bit you’ll be throwing away.
The technique that saves bits regardless of what you buy
Speed kills metal bits faster than anything else. The instinct is to run the drill fast because that’s how wood behaves — faster feels more efficient. Metal is the opposite. High RPM generates heat, heat is what actually dulls the cutting edge (not abrasion), and a dull bit then generates even more heat in a loop that ends with a blue, ruined tip. Drop your speed, use a cutting lubricant (even light machine oil helps), and let the bit do the work instead of leaning on it. A $15 cobalt bit run correctly will outlast a $40 bit run too fast.
